Method and Device for Executing Harq in Tdd-Based Wireless Communication System

1. A method of performing, by a user equipment to which a plurality of serving cells based on Time Division Duplex (TDD) has been allocated, a hybrid automatic repeat request (HARQ), the method comprising: receiving an uplink (UL) grant for a first subframe of a second serving cell through a first serving cell; transmitting UL data in the first subframe of the second serving cell based on the UL grant; and performing a non-adaptive retransmission for the UL data in a second subframe of the second serving cell if a not-acknowledgement (NACK) for the UL data is received through a physical HARQ indicator channel (PHICH) in a subframe i of the first serving cell, wherein the first serving cell and the second serving cell use different uplink-downlink (UL-DL) configurations, and each of the UL-DL configurations is information on which each subframe within a TDD frame is configured as an UL subframe, a DL subframe or a special subframe, and wherein if a PHICH resource corresponding to the UL data is not present in the subframe i, the non-adaptive retransmission is not allowed in the second subframe of the second serving cell.

2. A method of performing, by a user equipment to which a plurality of serving cells based on Time Division Duplex (TDD) has been allocated, a hybrid automatic repeat request (HARD), the method comprising: receiving an uplink (UL) grant for a first subframe of a second serving cell through a first serving cell; transmitting first UL data in the first subframe of the second serving cell based on the UL grant; and performing a non-adaptive retransmission for the first UL data in a second subframe of the second serving cell if a not-acknowledgement (NACK) for the first UL data is received through a physical HARQ indicator channel (PHICH) in a subframe i of the first serving cell, wherein the first serving cell and the second serving cell use different uplink-downlink (UL-DL) configurations, and each of the UL-DL configurations is information on which each subframe within a TDD frame is configured as an UL subframe, a DL subframe or a special subframe, wherein if a PHICH resource corresponding to the first UL data is not present in the subframe i, the non-adaptive retransmission is not allowed in the second subframe of the second serving cell, wherein if an UL grant for the second subframe is received in the first serving cell, the UL grant for the second subframe comprising information indicative of whether or not the first UL data is to be retransmitted, wherein if the information indicative of whether or not the UL data is to be retransmitted indicates retransmission, the first UL data is retransmitted in the second subframe, and wherein if the information indicative of whether or not the UL data is to be retransmitted indicates new transmission, a second UL data is transmitted in the second subframe.

3. The method of claim 2 , wherein in a case of a subframe in which the uplink grant for the second subframe is received in the first serving cell, the user equipment decodes only the uplink grant for the second subframe without attempting to receive a physical hybrid-ARQ indicator channel (PHICH).

4. The method of claim 2 , wherein a subframe of the first serving cell in which the uplink grant for the second subframe is received is any one of subframes indicated by D in a table below: UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 1 D D 2 D D D D D D 3 D D D D 4 D D D D D D 5 D D D D D D D D 6 .

5. User equipment, comprising: a Radio Frequency (RF) unit configured to transmit and receive radio signals; and a processor connected to the RF unit, wherein the processor is configured to: receive an uplink (UL) grant for a first subframe of a second serving cell through a first serving cell, transmit UL data in the first subframe of the second serving cell based on the UL grant, and perform a non-adaptive retransmission for the UL data in a second subframe of the second serving cell if a not-acknowledgement (NACK) for the UL data is received through a physical a hybrid automatic repeat request (HARQ) indicator channel (PHICH) in a subframe i of the first serving cell, wherein the first serving cell and the second serving cell use different uplink-downlink (UL-DL) configurations, and each of the UL-DL configurations is information on which each subframe within a Time Division Duplex (TDD) frame is configured as an UL subframe, a DL subframe or a special subframe, and wherein if a PHICH resource corresponding to the UL data is not present in the subframe i, the non-adaptive retransmission is not allowed in the second subframe of the second serving cell.

6. The method of claim 1 , wherein if a UL grant indicating a retransmission of the UL data is received in the subframe i, an adaptive retransmission for the UL data is performed in the second subframe of the second serving cell.

7. The method of claim 1 , wherein the first serving cell and the second serving cell use two different UL-DL configurations of UL-DL configurations 0-6 shown in a table below: DL-to-UL switch- UL-DL point Subframe n configuration periodicity 0 5 ms 1 5 ms 2 5 ms 3 10 ms 4 10 ms 5 10 ms 6 5 ms .

8. The method of claim 1 , wherein the subframe i is a subframe located between the first subframe and the second subframe.

9. The method of claim 1 , wherein if a PHICH resource corresponding to the UL data and an UL grant are not present in the subframe i, the user equipment does not perform any UL transmission.